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 A012342 tan(arcsin(x)*arcsin(x))=2/2!*x^2+8/4!*x^4+368/6!*x^6+18048/8!*x^8... 1

%I

%S 0,2,8,368,18048,1827072,253363200,50403563520,13158813696000,

%T 4414765984972800,1841972633056051200,936689336904269168640,

%U 569861032837432328847360,408713488929007199437455360

%N tan(arcsin(x)*arcsin(x))=2/2!*x^2+8/4!*x^4+368/6!*x^6+18048/8!*x^8...

%H Vaclav Kotesovec, <a href="/A012342/b012342.txt">Table of n, a(n) for n = 0..222</a>

%H Vaclav Kotesovec, <a href="/A012342/a012342.jpg">Graph - e.g.f. in the complex plane (absolute values)</a>

%F a(n) ~ sqrt(2) * cos(sqrt(Pi/2)) * (2*n)! / (sqrt(Pi) * (sin(sqrt(Pi/2)))^(2*n+1)). - _Vaclav Kotesovec_, Feb 06 2015

%t nn = 20; Table[(CoefficientList[Series[Tan[ArcSin[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* _Vaclav Kotesovec_, Feb 06 2015 *)

%K nonn

%O 0,2

%A Patrick Demichel (patrick.demichel(AT)hp.com)

%E a(0)=0 prepended by _Vaclav Kotesovec_, Feb 06 2015

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Last modified December 2 15:42 EST 2022. Contains 358510 sequences. (Running on oeis4.)